This invention generally relates to elastically deformable lenses and, more particularly, to devices that are capable of focusing an elastically deformable lens.
Variable focus lenses and lens systems have come to be extensively used because they provide convenient solutions to problems that frequently arise in applied optics. Optical systems incorporating such lenses can, for example, provide a focused image of objects at varying distances from the lens on an image plane without changing the distance between the lens and the image plane. They can also be used in optical systems that provide varying magnification without changing lenses.
A number of types of variable focus lenses have been devised. However, the design most widely used at present in optical instruments such as cameras, telescopes, binoculars and micro-scopes is a multi-element lens wherein the focal length is varied by changing the internal spacing of one or more of the elements along the optical axis.
Another class of variable focus lenses relies on changes in the refracting power of a single lens element effected by changes in the curvature of the refracting surfaces or the refractive index of the lens material.
U.S. Pat. No. 6,038,080 for xe2x80x9cVARIABLE FOCUS LENS BY SMALL CHANGES OF THE EQUATORIAL LENS DIAMETERxe2x80x9d issued on Mar. 14, 2000 to Ronald A. Schachar and U.S. Pat. No. 6,246,528 for xe2x80x9cVARIABLE FOCUS LENS BY SMALL CHANGES OF THE EQUATORIAL LENS DIAMETERxe2x80x9d issued on Jun. 12, 2001 to Ronald A. Schachar describe an elastically deformable lens of variable focal length that can be focused by making small changes in the equatorial lens diameter. The elastically deformable lens is focused by varying the optical power of the lens by radial stretching of the lens over a few percent of its diameter. The lens comprises a transparent elastic body having two opposed optical refracting surfaces intersecting an optical axis. Incorporated into a periphery surrounding the optical axis are means for expanding the periphery of the elastic body in a plane generally perpendicular to the optical axis by an amount not exceeding about five percent (5%) of its relaxed diameter. The optical power of the elastically deformable lens may be increased by expanding the periphery of the lens in a plane generally perpendicular to the optical axis of the lens by an amount not exceeding about five percent (5%) of its relaxed diameter.
Presently existing systems and methods for focusing an elastically deformable lens are not capable of focusing a relatively small lens that is located within a restricted volume. For example, consider an elastically deformable lens that is approximately the size of the lens of a human eye. Such a lens has an optically active diameter that spans three to five millimeters (3 mm to 5 mm). It has been shown that the application of tensile and compressive forces at various locations around the periphery of such a lens induces surface curvature that causes the lens to have the ability to focus on near or far objects with an optical power that exceeds forty (40) diopters. If such a lens could be implanted and made to operate within a human eye, it could serve as a replacement lens for persons who have lost a lens through disease or accident.
The prior art systems and methods for focusing such a lens are too large, bulky, expensive, and impractical to be used to accomplish such a task. The prior art hardware for focusing such a lens is much too large to be implanted within a human eye.
Therefore there is a need in the art for an improved system and method for focusing an elastically deformable lens. There is also a need in the art for an improved system and method for focusing a relatively small lens that is located within a restricted volume. There is also a need in the art for an improved system and method for focusing an elastically deformable variable focus lens that is inexpensive, accurate and small in size.
The present invention comprises a system and method for focusing an elastically deformable lens using a plurality of micro-electro mechanical system (MEMS) microengine assemblies to vary the optical power of the lens by radially stretching the lens over a few percent of the diameter of the lens. The lens comprises a transparent elastic body having two opposed optical refracting surfaces intersecting an optical axis. The microengine assemblies are coupled to the periphery of the lens. Each microengine assembly comprises an electrothermally actuated microengine and a latching element that couples the microengine to the periphery of the lens. In response to receiving control signals from a controller, each microengine provides mechanical translations to move the periphery of the lens either forward or backward to provide the compressive or tensile forces to focus the lens.
Each microengine assembly is capable of functioning in two distinct modes. In the first mode, each microengine assembly is capable of producing macroscopic mechanical translations on the order of two hundred microns (200 xcexcm) in order to engage the latching element of the microengine assembly with an aperture through the periphery of the lens. In the second mode, each microengine assembly is capable of producing microscopic mechanical translations on the order of one micron (1 xcexcm) in order to focus the lens.
It is an object of the present invention to provide a system and method for focusing an elastically deformable variable focus lens.
It is another object of the present invention to provide a system and method for focusing an elastically deformable variable focus lens in which small changes in the equatorial diameter of the lens are produced by a plurality of micro-electro mechanical systems (MEMS) microengine assemblies.
It is also an object of the present invention to provide a system and method for focusing an elastically deformable variable focus lens that is inexpensive, accurate and small in size.
Further objects of the invention will become apparent from the description of the invention that follows.